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The current improvements in aerosol mass spectrometers in resolution and sensitivity, and the analytical tools for mass spectra deconvolution, have enabled the in-depth analysis of ambient organic aerosol (OA) properties. Although OA constitutes a major fraction of ambient aerosol, its properties are determined to a great extent by the mixing characteristics of both organic and inorganic components of ambient aerosol. This work applies a new methodology to a year-long ACSM dataset to assess the sources of organic and total non-refractory species in the Athens background aerosol and provides insights into the interactions between organic and inorganic species. The use of innovative tools for applying positive matrix factorization (PMF, rolling window) enables the study of the temporal variability of the contribution of these sources and seasonal changes in their composition. The mass spectra of both organic and inorganic aerosol were obtained by a time-of-flight aerosol mass spectrometer (ToF-ACSM) for PMF analysis. The results revealed five factors when organic aerosol was analysed separately. Three of them were primary OA factors: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA) and biomass burning organic aerosol (BBOA). The remaining two were secondary, less and more oxidized oxygenated organic aerosol (LO-OOA and MO-OOA respectively). The relative contributions of these factors were HOA 15 %, COA 18 %, BBOA 9 %, MO-OOA 34 % and LO-OOA 24 % (yearly averaged). When a combined organic and inorganic aerosol matrix was analysed, two additional factors were identified that were mainly composed of ammonium sulfate (83.5 %) and ammonium nitrate (73 %). Moreover, two secondary factors were resolved, containing both organics and inorganics and were named more (MOA) and less oxidized aerosol (LOA). The relative contributions on a yearly average of these factors were HOA 7 %, COA 9 %, BBOA 3 %, ammonium nitrate 3 %, ammonium sulfate 28 %, MOA 24 % and LOA 26 %.

The representation of orographic clouds in numerical weather prediction models remains a great challenge, as a consequence of our incomplete understanding of the microphysical processes acting on them and the complex interactions between the large-scale and orographic flow dynamics. Mixed-phase conditions are frequently occurring in orographic clouds, highlighting the importance of correctly simulating the microphysical evolution of ice- and liquid-phase hydrometeors. In this study we employ the mesoscale Weather Research and Forecasting (WRF) model to investigate the drivers of intense snowfall events observed during the Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISHTO) campaign, that took place from Fall 2021 to Spring 2022 at Mount Helmos in Peloponnese, Greece. Vertical profiles of reflectivity, Doppler velocity, as well as full Doppler spectra measured by a vertically pointing W-band (94 GHz) Doppler cloud radar, in synergy with Doppler and aerosol depolarization lidar data, help gain insight into the snowfall microphysics involved and set the basis for evaluating the performance of the WRF model. A radar simulator coupled with WRF enables the direct comparison between the mesoscale simulations and remote sensing products, and allows us to find the optimal model set-up that minimizes deviations from the observations. Comparing the modeled ice crystal number concentrations (ICNCs) with the Ice Nucleating Particles (INPs) measured in-situ at the Helmos High Altitude Monitoring Station (2314 m, 42°N 05' 30'', 34°E 14' 25'') by the Portable Ice Nucleation Experiment (PINE) instrument, we seek to quantify the ice enhancement factors due to secondary ice production (SIP) or seeding ice particles and their potential role in enhancing orographic precipitation. The synergy between high-resolution modeling and radar observations gives us the opportunity to infer SIP signatures from remote sensing observations, which is an important outcome given the abundance of the latter.

This study presents part of the results of the CALISHTO campaign (Cloud-AerosoL InteractionS in the Helmos Background TropOsphere) that took place in autumn 2021 at the free-troposphere high-altitude Helmos station (2314 m a.s.l.). A Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM, Aerodyne) was deployed among other instruments (AE31, PVM-100, SMPS, EC/OC analyzer) in the framework of the campaign. The chemical characterization of the non-refractory PM1 (NR-PM1), the influence from the Boundary Layer / Free Troposphere, the origin of the incoming masses and the influence of clouds were studied. The sources of PM1 including the non-refractory species of ACSM (organics and inorganics) combined with the equivalent black carbon were also investigated by applying the PMF model to the combined dataset. The results showed that there is a great variability of aerosol characteristics depending on the height of the PBL and the origin of the air masses. During September the station was exposed to PBL emissions, and thus displayed much higher mass concentrations of NR-PM1 than October and November. Concerning the sources of PM1, different types were identified with ammonium sulphate and oxygenated organics being predominant, as expected for aged aerosol with the degree of ageing investigated against air mass origin and microphysical parameters.

The scope of this work is to quantify the emission rate of Secondary Sulfate across a wide region in the Northern hemisphere, mainly in Europe and Western Asia. The data employed are deducted by Positive Matrix Factorization (PMF) on a PM2.5 chemical composition dataset from 16 European and Asian cities for the period 2014 to 2016. The spatial resolution of the method corresponds to the geographic grid cell size of the Lagrangian particle dispersion model (FLEXPART) which was utilized for the air mass backward simulations. The area covered is also related to the location of the 16 cities under study.Species with an aerodynamic geometric mean diameter of 400 nm and geometric standard deviation of 1.6 were used to model the Secondary Sulfate aerosol transport. Generalized Tikhonov regularization was applied so as to acquire potential source areas and quantify their emission rate. The results acquired by this process indicate a significant source area for Secondary Sulfate on the East of the Caspian Sea. The maximum emission rate in that area is as high as 10 g m-2 s-1. Significant source areas also include South Poland and the Balkans. The results display many similarities to the SO2 emission map provided by ECLIPSE database. AcknowledgementsThis research has been funded by the program “RER/1/015 - Apportioning air pollution sources on a regional scale”, 2016 - 2017. ReferencesVratolis, S., Diapouli, E., Manousakas, M. I., Almeida, S. M., Beslic, I., Kertesz, Z., Samek, L., and Eleftheriadis, K.: A new method for the quantification of ambient particulate matter emissions, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2022-843, in review, 2023.

It is well established that the Aerosol-Cloud Interaction (ACI) processes play a key-role in global precipitation and are a strong modulator of cloud radiative forcing and climate, and yet remain poorly understood despite decades of research. Aerosol-cloud interactions are one of the most uncertain aspects of anthropogenic climate change (Seinfeld et al., 2016a; IPCC, 2021).Global datasets on cloud microphysical state – especially droplet number concentration and size distribution – provide important constraints that are required for reducing the ACI uncertainty. Recently, Quaas et al. (2020) showed that satellite remote sensing is the only approach that offers the potential of obtaining global datasets with frequent coverage; current retrieval algorithms, however, carry many uncertainties and require constraints that can only be addressed with in situ and/or ground-based remote sensing observations.Our study aims to evaluate retrievals of cloud droplet number (Nd), effective radius (reff) and optical thickness provided by the CLoud property dAtAset using SEVIRI - Edition 3 (CLAAS-3) cloud products of Satellite Application Facility on Climate Monitoring (CM SAF). For this reason, we used co-located in-situ measurements of aerosols and cloud dynamical properties in conjunction with remote sensing observations at the high-altitude regional background station Hellenic Atmospheric Aerosol and Climate Change (HAC2) during the Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISHTO) campaign, which took place from Fall 2021 to Spring 2022 at Mount Helmos in Peloponnese, Greece (https://calishto.panacea-ri.gr/).In this study, we adopt an approach first applied to droplet retrievals in an urban environment (Foskinis et al. 2022). Ground-based remote sensing instrumentation involved includes a Doppler depolarization lidar (HALO) at 1550 nm to provide the vertical velocity (w) of the air masses, a Doppler cloud radar at 94 GHz (RPG) to provide the equivalent reflectivity factor (Z), and the mean Doppler velocity (VD), and a radiometer at 89 GHz provides the liquid water path (LWP). Furthermore, the in-situ instrumentations employed a co-located scanning Mobility Particle Size (SMPS) measuring the size distribution of submicron aerosol, and a Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) to provide the aerosol chemical composition of the aerosols. The in-situ dataset together with the airmass vertical velocity distributions are used as input to a state-of-the art parameterization to predict the droplet number (Nd) in clouds formed in the vicinity of the HAC2 station. Retrievals with the the CLAAS-3 cloud properties product from CMSAF are then evaluated with in-situ observations carried out with a cloud probe instrument (PVM-100) and the droplet number calculations.Compared to our previous study (Foskinis et al. 2022), this study is implemented in a different physical system, where we examined again the dependence of the Spectral Dispersion of Droplets (SDD) on Nd and we found a new optimized expression between SDD-Nd which can be used on the established droplet number retrieval algorithm (Bennartz et al., 2007) for non-precipitating planetary boundary layer clouds in order to mitigate the bias.

Homogeneous nucleation is an important source of new particles in the atmosphere worldwide. The resulting newly formed stable nuclei can grow to larger sizes and affect air quality and climate. Unexpected significant spatial variability of the nucleation frequency has been observed in Greece in the only previous relative study: very high frequency in Thessaloniki, intermediate in Eastern Crete and low in Patras (Patoulias et al., 2018). Our hypothesis is that Greece may be an excellent natural laboratory to investigate the factors affecting nucleation and to understand the reasons behind this surprising variability.Extensive continuous aerosol size distribution measurements took place during two summers (2020 and 2021) as part of the PANACEA project in 11 different locations: Patras, Xanthi, Ioannina, Finokalia, Athens, Thessaloniki, Sifnos, Chania, Costa Navarino (NEO), Lesvos and Mt. Helmos. The instrumentation used included a number of scanning mobility particle sizers (SMPS) for the measurement of the particles and a suite of gas monitors for measuring SO2, NOx, NH3 and CO in selected sites. A particle size magnifier (PSM) was deployed in the Patras site during the 2021 campaign, providing valuable information regarding nanoparticles with diameter down to 1 nm.The observations suggest that indeed the nucleation frequency during summer in Greece varies from close to zero in the southwestern parts of the country to more than 70% in the northern central and eastern regions. The analysis of the measurements in the various sites shows that the proximity to coal-fired power plants is a major factor affecting the nucleation frequency. North-eastern and northern airmasses passing over such locations in the Balkans and Western Turkey where strongly associated with nucleation. Also, the emissions of ammonia during summer, suggest that it exhibits similar spatial gradients with the observed nucleation frequency and may be controlling nucleation in Greece. The corresponding measurements in each site, were also used to estimate the corresponding particle growth and formation rates and the condensation and coagulation sinks.The detailed analysis of the measurements in Patras, Western Greece, suggests that nucleation was infrequent in this location (12%), but particles that were formed a few hours earlier over central Greece are often transported to this area after they have grown to sizes of 20-30 nm. The air mass history suggested that new particle formation often took place in the vicinity of an area 100-150 km northeast of Patras, with significant agricultural activity and therefore, high emissions of ammonia and amines. The relatively high emissions of biogenic volatile organic compounds in Western Greece where Patras is located, did not appear to assist in the local formation of new particles.

In this study, we investigated the impact of urban emission sources on the chemical composition of ambient particulate matter (PM) as well as the associated oxidative potential. We collected six sets of PM samples in five urban location sites around the world over long time periods varying from weeks to months, intentionally selected for their PM to be dominated by unique emission sources: (1) PM

The role of enteral feeding with fiber-enriched feeds in minimizing infections, shortening length of hospital stay (LOHS), and preventing or treating feeding complications has been widely researched. However, there is limited evidence to evaluate the role of fiber-enriched enteral feeding in gastrointestinal surgery patients postoperatively. This systematic review aims to identify the role of fiber-enriched enteral feeds on postoperative feeding complications of diarrhea, nausea and vomiting, abdominal distension, flatulence, cramps, LOHS, and infection rates after gastrointestinal surgery. A systematic literature search was conducted using MEDLINE, CINAHL, and Cochrane Library. Manual reference lists were searched on identified studies and the SCOPUS database. Randomized controlled trials (RCTs) conducted on any gastrointestinal surgery type that included enteral nutrition with high-fiber enteral feeds and/or fiber supplements were included. All studies included were screened for risk of bias with Cochrane's risk-of-bias tool, and data were extracted with Cochrane Collaboration's data extraction tool. In total, 3 RCTs out of 231 screened citations including fiber-enriched feeds and probiotics were included in this review. No significant effect on LOHS or postoperative infections was found. No safety risks were identified. Limited, low-quality evidence suggests fiber-enriched feeds may minimize diarrhea incidence. The effects of fiber-enriched feeds postoperatively in gastrointestinal surgery remain under-researched. Studies evaluating fiber and probiotics were low quality and at high risk of bias because of the misreporting of outcomes and the lack of detailed outlines of probiotic strains utilized. However, fiber-enriched enteral feeding appears safe, may yield benefits, and is recommended in stable gastrointestinal surgical patients.

Remote sensing has been a key resource for developing extensive and detailed datasets for studying and constraining aerosol-cloud-climate interactions. However, aerosol-cloud collocation challenges, algorithm limitations, as well as difficulties in unraveling dynamic from aerosol-related effects on cloud microphysics, have long challenged precise retrievals of cloud droplet number concentrations. By combining a series of remote sensing techniques and in situ measurements at ground level, we developed a semi-automated approach that can address several retrieval issues for a robust estimation of cloud droplet number for non-precipitating Planetary Boundary Layer (PBL) clouds. The approach is based on satellite retrievals of the PBL cloud droplet number (Ndsat) using the geostationary meteorological satellite data of the Optimal Cloud Analysis (OCA) product, which is obtained by the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) of the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT). The parameters of the retrieval are optimized through closure with droplet number obtained from a combination of ground-based remote sensing data and in situ observations at ground level. More specifically, the remote sensing data are used to retrieve cloud-scale vertical velocity, and the in situ aerosol measurements at ground level were used constrain as input to a state-of-the-art droplet activation parameterization to predict the respective Cloud Condensation Nuclei (CCN) spectra, cloud maximum supersaturation and droplet number concentration (Nd), accounting for the effects of vertical velocity distribution and lateral entrainment. Closure studies between collocated Nd and Ndsat are then used to evaluate exising droplet spectral width parameters used for the retrieval of droplet number, and determine the optimal values for retrieval. This methodology, used to study aerosol-cloud interactions for non-precipitating clouds formed over the Athens Metropolitan Area (AMA), Greece from March to May 2020, shows that droplet closure can be achieved to within 30%, comparable to the level of closure obtained in many in situ studies. Given this, the ease of applying this approach with satellite data obtained from SEVIRI with high temporal (15 min) and spatial resolution (3.6 km × 4.6 km), opens the possibility of continuous and reliable Ndsat, giving rise to high value datasets for aerosol-cloud-climate interaction studies.

Black carbon (BC) from incomplete combustion of biomass or fossil fuels is the strongest absorbing aerosol component in the atmosphere. Optical properties of BC are essential in climate models for quantification of their impact on radiative forcing. The global climate models, however, consider BC to be spherical particles which causes uncertainties in their optical properties. Based on this, an increasing number of model-based studies provide databases and parametrization schemes for the optical properties of BC using more realistic fractal aggregate morphologies. In this study, the reliability of the different modelling techniques of BC was investigated by comparing them to laboratory measurements. In the first step, the modeling techniques were examined for bare BC particles, and in the second step, for BC particles with organic material. A total of six morphological representations of BC particles were compared, three each for spherical and fractal aggregate morphologies. The BC fractal aggregate is usually modelled using monodispersed particles since their optical simulations are computationally expensive. In such studies, the modelled optical properties showed a 25 % uncertainty in using the monodisperse size method. It is shown that using the polydisperse size distribution in combination with fractal aggregate morphology reduces the discrepancy between modelled and measured particle light absorption coefficient σabs to 10 %, for particles with volume mean mobility diameters between 60–160 nm. However, for particles larger than 100 nm, the Absorption Ångström Exponent (AAE) calculated by using a spherical morphology was more consistent with the measured value. Furthermore, the sensitivities of the BC optical properties to the various model input parameters such as the real and imaginary parts of the refractive index (mre and mim), the fractal dimension (Df), and the primary particle radius (app) of an aggregate were investigated. The modelled optical properties of BC are well aligned with laboratory-measured values when the following assumptions are used in the fractal aggregate representation: mre between 1.6 to 2; mim between 0.50 to 1; Df from 1.7 to 1.9, and app between 10 to 14 nm. Overall, this study provides experimental support for emphasizing the use of an appropriate size representation (polydisperse size method) and an appropriate morphological representation (aggregate morphology) for optical modelling and parametrization scheme development of BC.

International audience; On August 8, 2019, an explosion of a military missile occurred at the Nenoksa (also transcribed as Nyonoksa) Missile Test Center (Russian Federation). Russian authorities confirmed arelease of radioactive material in the course of this incident,which fueled rumors that it could have involved a nuclear-propelled missile of the Burevestnik/Skyfall type. In this study,our radioanalytical efforts are summarized searching for the“smoking gun” of the incident. These included the gamma-measurements of air filters from two vessels that were in someproximity to the event as well as one Greek high-volume airfilter. In addition, we tested the hypothesis that radioactive 42Ar may have been used to operate a radiothermal generator. If the incident had released 42Ar, it may have become detectable by measuring characteristic gamma radiation emitted from a tank containing liquefied atmospheric argon. No traces what so ever were found that could provide clues about the release. It is possible that the presumably small amounts of radionuclides released from either a small nuclear reactor or a powerful radionuclide source dispersed quickly over Russian territory to non-detectable levels before reaching any of our assayed samples.

The concentrations, size distributions, and elemental compositions of atmospheric aerosol particles over a small but representative (in terms of size, population, and geographical characteristics) insular coastal city in the North Aegean Sea were measured during winter and summer. Mean PM2.0 and PM1.0 concentrations at the city centre were respectively 26 and 21 μg m−3 during the cold period, and 21 and 15 μg m−3 during the warm period. Although these concentrations are considerably lower compared to corresponding values of PM2.5 and PM1.0 recorded in large cities in the region, they are still very close to the mean annual standards set by the EU for PM2.5. Higher average mass concentrations (by ca. 26–36% for Total Suspended Particles, PM2.0 and PM1.0) were observed in the cold period compared to those in the warm period due to the additional emissions from domestic heating and the weaker atmospheric dilution. The elemental composition measurements showed that crustal and anthropogenic elements (i.e., K, Ca, Ti, Mg, Fe, As, S) in the collected particle samples were also enriched when polluted air masses were transported from Northeastern Turkey. These measurements also showed that natural sources contribute sea-salt and re-suspended soil to the particulate matter load in the city's atmosphere. Non-exhaust traffic emission sources were also found to be an important contributor, as indicated by the good correlations (R2 = 0.40–0.91) between crustal and traffic-related elements (i.e., Zn, Cr, Cu, and Mn). Overall, PM measurements in the urban environment in the region are relatively high, being influenced by both local sources and long-transported air masses.

Summarization: Investigation of the personal dose caused by air pollution in children is important due to their vulnerability. Exposure to PM10 and its components, particularly certain metals, may pose significant health risks therefore many studies have focused on measuring the ambient indoor/outdoor PM10 concentrations in school environments. However, little research has aimed at assessing the resultant personal dose. Hence, this study applied a dosimetry model (ExDoM2) to predict the personal dose received by students in five primary schools in Lisbon, Portugal. The calculations were performed for PM10 and PM10-bound metals, and the exposed subjects were assumed to be 10-year-old nose breathers. A realistic exposure scenario involving three different settings (the indoor home, indoor school and outdoor school microenvironments) was implemented for an exposure period of one week (Monday–Sunday). Although the students spent only 24% of their total time inside a school (vs. 73% at home), this environment contributed 44% on average to the weekly deposited dose of PM10, providing further evidence that indoor exposure at schools is a major contributor to the total dose. The modeling results showed that the cumulative deposited doses in the respiratory tract (RT) reached as high as 2,004 μg, 0.16 μg, 0.65 μg, 0.58 μg and 0.06 μg for PM10, Cr, Mn, Pb and Ni, respectively, after one week. Presented on: Aerosol and Air Quality Research

Well-type high-purity germanium detectors are well suited for the analysis of small samples, as they combine high detection efficiency with low background radiation. The well geometry however makes efficiency calibration more difficult than that of ordinary HPGe detectors, due to intense true coincidence and possibly random summing effects. Such a detector has been installed at the Environmental Radioactivity Laboratory of the National Centre for Scientific Research "Demokritos". For the calibration of this detector, experimental and Monte Carlo simulation techniques were applied. To this end, calibration sources were produced from the radionuclides available at the Environmental Radioactivity Laboratory. Starting from the geometrical characteristics of the detector as provided by the manufacturer, using the calibration sources and applying Monte Carlo simulation techniques, the detector was characterized and peak efficiency, as well as total-to-peak calibration curves were produced. The results of the calibration finally obtained by simulation are found to be in good agreement with the respective experimental calibration results.

A sensitive analytical method has been developed and validated for the determination of 16 polyfluorinated alkyl substances (PFAS) in fine airborne particulate matter (PM

This study is supported by the RI-URBANS project (Research Infrastructures Services Reinforcing Air Quality Monitoring Capacities in European Urban & Industrial Areas, European Union’s Horizon 2020 research and innovation programme, Green Deal, European Commission, under grant agreement No 101036245). The authors would like to thank ACTRIS (The Aerosol, Clouds and Trace Gases Research Infrastructure), especially the EBAS Data Centre, for providing datasets for the study. The authors would like to thank also the support from “Agencia Estatal de Investigación” from the Spanish Ministry of Science and Innovation, and FEDER funds under the projects CAIAC (PID2019-108990RB-I00); and the Generalitat de Catalunya (AGAUR 2021 SGR00447) and the Direcció General de Territori. This study is partly funded by the National Institute for Health Research (NIHR) Health Protection Research Unit in Environmental Exposures and Health, a partnership between UK Health Security Agency (UKHSA) and Imperial College London. The views expressed are those of the author(s) and not necessarily those of the NIHR, UKHSA, or the Department of Health and Social Care. The work in Rochester, NY was funded by the New York State Energy Research and Development Authority under contracts #59802 and 125993. This research is also partly supported by the Hungarian Research, Development and Innovation Office (grant no. K132254). We thank the Hessian Agency for Nature Conservation, Environment and Geology (HLNUG), Wiesbaden, Germany for providing concentrations of ancillary pollutants of urban background station at Darmstadt. The Stockholm traffic station (Hornsgatan) datasets were provided thanks to the nPETS project (grant agreement no. 954377) funded by the European Union (EU)., Supplementary data to this article can be found online at https://doi.org/10.1016/j.envint.2023.107744, The 2017–2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus. The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping. Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation. PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of, RI-URBANS project, ACTRIS, EBAS Data Centre, “Agencia Estatal de Investigación" Spanish Ministry of Science and Innovation, FEDER projects CAIAC (PID2019-108990RB-I00), Generalitat de Catalunya (AGAUR 2021 SGR00447) and the Direcció General de Territori, National Institute for Health Research (NIHR) Health Protection Research Unit in Environmental Exposures and Health, New York State Energy Research and Development Authority, Hungarian Research, Development and Innovation Office, CGIAR European Commission 954377

A new gas inlet port combined with a novel ionization scheme have been developed and coupled to a high-resolution time-of-flight mass spectrometer (TOF MS) for the detection and measurement of atmospheric volatile (VOCs) and intermediate volatility organic compounds (IVOCs). Ions are produced predominantly by charge transfer reactions in a low-temperature plasma ionization source with minimal fragmentation. Enhanced sensitivity is accomplished by incorporating an increased-size inlet capillary in a transverse arrangement to maximize throughput in the ionization source. Additional design aspects of the new mass spectrometer enabling superior transmission include a large acceptance ion funnel and a segmented radio frequency (RF) ion guide with increased space charge storage capacity. An orthogonal TOF analyzer equipped with a two-stage reflectron and tuned to second order is employed for the determination of the mass-to-charge ratio of the ions, with a mass resolving power of >20 k at mass 500 Th. The performance of the instrument was evaluated in tests using VOC standards and in atmospheric chamber experiments to demonstrate the ability to measure a wide range of organic compounds with different functional groups. Linear signal response is demonstrated over a wide range of VOCs used in the calibration processes in the ppb range, while the instrument exhibits linear response in the ppt range as well. Detection limits as low as 1 ppt are accomplished. The potential applications of this new TOF MS instrument were demonstrated in a pilot atmospheric simulation chamber experiment.

As explained in the latest Arctic Monitoring and Assessment Programme (AMAP) report released in early 2021, the Arctic has warmed 3 times more quickly than the planet as a whole, as well as faster than previously thought. The Siberian Arctic is of great interest mainly because observations are sparse or largely lacking. A research aerosol station has been developed on Bely Island (Kara Sea) in western Siberia. Measurements of equivalent black carbon (EBC) concentrations were carried out at the “Island Bely” station continuously from August 2019 to November 2020. The source origin of the measured EBC and the main contributing sources were assessed using atmospheric transport modeling coupled with the most updated emission inventories for anthropogenic and biomass burning sources of BC. The obtained climatology for BC during the period of measurements showed an apparent seasonal variation with the highest concentrations between December and April (60 ± 92 ng m−3) and the lowest between June and September (18 ± 72 ng m−3), typical of the Arctic haze seasonality reported elsewhere. When air masses arrived at the station through the biggest oil and gas extraction regions of Kazakhstan, Volga-Ural, Komi, Nenets and western Siberia, BC contribution from gas flaring dominated over domestic, industrial and traffic sectors, ranging from 47 % to 68 %, with a maximum contribution in January. When air was transported from Europe during the cold season, emissions from transportation were more important. Accordingly, shipping emissions increased due to the touristic cruise activities and the ice retreat in summertime. Biomass burning (BB) played the biggest role between April and October, contributing 81 % at maximum in July. Long-range transport of BB aerosols appeared to induce large variability to the absorption Ångström exponent (AAE) with values > 1.0 (excluding outliers). As regards the continental contribution to surface BC at the Island Bely station, Russian emissions dominated during the whole year, while European and Asian ones contributed up to 20 % in the cold period. Quantification of several pollution episodes showed an increasing trend in surface concentrations and frequency during the cold period as the station is directly in the Siberian gateway of the highest anthropogenic pollution sources to the Russian Arctic.

Air quality in urban areas and megacities is dependent on emissions, physicochemical process and atmospheric conditions in a complex manner. The impact on air quality metrics of the COVID-19 lockdown measures was evaluated during two periods in Athens, Greece. The first period involved stoppage of educational and recreational activities and the second severe restrictions to all but necessary transport and workplace activities. Fresh traffic emissions and their aerosol products in terms of ultrafine nuclei particles and nitrates showed the most significant reduction especially during the 2nd period (40–50%). Carbonaceous aerosol both from fossil fuel emissions and biomass burning, as well as aging ultrafine and accumulation mode particles showed an increase of 10–20% of average before showing a decline (5 to 30%). It is found that removal of small nuclei and Aitken modes increased growth rates and migration of condensable species to larger particles maintaining aerosol volume.

The activity size distributions of the natural radionuclide tracer 7Be in different size fractions ( 9.0 μm) were determined at four different site places in Northern Italy during the four seasons of the year 2011. One cascade impactor operated at the LASA-station considered the reference station and the other used for simultaneous measurements at the three other sites. Three sets of independent samples were collected during every season of the year 2011. The initial activity distribution inverted into smooth size distribution. The model parameters successfully defined to obtain the best fit-curve and two or three modes were resolved, with the predominant fit at the accumulation range. The lowest Activity Median Aerodynamic Diameter (AMAD) values were observed during summer. The AMAD values were anticorrelated with 7Be activities, while they were correlated with Relative Humidity. Similar AMAD values in suburban and urban regions were observed during all periods of the year. AMAD values of 7Be aerosol particles in areas with poor air quality were greater than those at the less polluted environments far from anthropogenic activities regions. This indicates that 7Be AMAD values could be used as an index of air quality conditions in areas like the Po Valley.

Particle number size distribution measurements were conducted during the summer of 2012 at City-Centre Urban Background (Patras-C), Urban Background (ICE-HT in Patras, DEM in Athens, EPT in Thessaloniki), and Regional Background stations (FIN in Crete). At the City-Centre Urban Background station, the average number distribution had a geometric mean diameter peak approximately at 60 nm and the highest number concentration, whereas at the Regional Background station and the Urban Background stations it displayed a major peak approximately at 100 nm, with the Regional Background station exhibiting the lowest number concentration. The particle number size distribution at each site was divided into size fractions and, based on their diurnal variation and previous studies, we concluded that the main sources for the City-Centre Urban Background station are traffic and the regional background concentration, for the Urban Background stations fresh traffic, aged traffic, cooking and the regional background concentration, and for the Regional Background station local activities (tourism, cooking) and regional background concentration. The median number concentration that is attributed to regional background concentration for the City-Centre Urban Background, the Urban Background and the Regional Background stations are respectively 13, 29 and 45% of the total number concentration. Nucleation events were identified at DEM station, where the newly formed particles accounted for 4% of the total particle concentration for the measurement period in the size range 10–20 nm, EPT, where they accounted for 12%, and FIN, where they accounted for 1%, respectively. New Particle Formation events contribution during summer to Condensation Cloud Nuclei were therefore insignificant in the Eastern Mediterranean. Modal analysis was performed on the number distributions and the results were classified in clusters. At the City-Centre Urban Background station, the cluster-source that dominated number concentration and frequency is related to fresh and aged traffic emissions, at the Urban Background stations aged traffic emissions, while at the Regional Background station number and frequency were dominated by the regional background concentration. Based on cluster analysis, 18% of the median number distribution was due to long range transport at the City-Centre Urban Background site, 37% at the Urban Background sites, and 59% at the Regional Background site. The Flexible Particle Dispersion Model (FLEXPART) was used in order to acquire geographic origin clusters and we concluded that the Etesian flow increases the median regional background number concentration in the Mediterranean basin by a factor of 2.5–4.

During the summer of 2012 a coordinated field campaign was conducted in multiple locations in Greece in order to characterize the ambient particulate matter (PM) levels, its chemical composition and the contribution of the regional and local sources. PM1, PM2.5 and PM10 samples were collected simultaneously at seven different sites in Greece: an urban and a suburban station in Patras, a suburban station in Thessaloniki, a suburban and an urban background station in Athens, a rural background station at the Navarino Environmental Observatory (NEO) in southwestern Peloponnese and a remote background site at Finokalia in the northeastern part of Crete. The sites were selected to facilitate the estimation of the contribution of the local emission sources and long range transport. Sulfate and organics were the major PM1 components in all sites suggesting that high sulfate levels still remain in parts of Europe. The photochemistry of the Eastern Mediterranean can convert rapidly the emitted sulphur dioxide to sulfate. Our analysis indicated significant sulfate production over the area, with high sulfate levels, especially in the remote site of Finokalia, associated with air masses that had passed over Turkey. There was high regional secondary organic aerosol production dominating organic aerosol levels even in a major city like Athens. High organic aerosol levels were associated with air masses that had crossed the Balkans with a significant biogenic component. The average PM2.5 concentration ranged from 13 to 18 μg m−3 in the different sites. There were unexpected significant gradients in the concentrations of secondary aerosol components in length scales of a few hundred kilometers. The low concentrations of measured PM2.5 nitrate are mostly organic nitrates and supermicrometer nitrate associated with sea-salt and dust. Dust was a significant PM10 constituent in all areas and was quite variable in space showing the importance of the local sources.

As a growing percentage of the population is working in office buildings worldwide, air quality in these indoor environments is becoming of particular importance for assessing health impacts from exposure to different pollutants. Apart from the common indoor air pollution sources, the presence of a variety of electronics such as printers, copier machines and other equipment in office buildings may present a high health risk because of their emissions of gases and particles. The aim of this study is to review and compare available measurements of the most commonly reported indoor particulate matter (PM) fractions in office environments and the methodological approaches that were used for the assessment of air quality and associated health effects. Data from forty-nine studies conducted in twenty-four countries around the world were included in this review. Half of these studies report measurements of indoor air pollution concentrations at a fixed point, with half of those using portable devices for assessing the personal exposure of employees in a direct way. The results showed that indoor concentrations for all air pollutants were higher than those measured outdoors, and that they increased during working hours. The average PM levels in offices ranged from 14 to 333 μg/m3 for particles having diameters up to 10 μm (PM10), and 4–227.44 μg/m3 for particles having diameters up to 2.5 μm (PM2.5). Results also showed that many health effects like eye irritation, dry throat, runny nose, sneezing, cough, tiredness, irritability, difficulty concentrating, headache, dizziness, and skin irritation reported through questionnaires by employees were associated with these pollutants, while being influenced by gender and environmental factors such as temperature and relative humidity.

Metropolitan urban areas in Greece and South Europe in general suffer from poor air quality because of a variety of factors favouring the accumulation of pollution. Despite a number of control measures implemented since the 1990s, resulting in reductions of atmospheric pollution and changes in emission source contributions, the financial crisis has altered this picture, adding complexity to the problem. An overview of results from several studies in a suburban area of Athens provides some lessons learned including strengths and weaknesses of receptor modelling using the positive matrix factorization (PMF) tool, as well as the observed changes in the various source contributions to PM10 and PM2.5. A comparison with past studies 5 and 10 years ago, with results from the cities of Porto, Barcelona, Florence and Milan, shows that biomass burning was the largest contributing source at urban background sites in Greece, while secondary aerosol formation (sulphate, nitrate and organics) was also a major contributing source for both size fractions at the suburban and urban background sites. Vehicular traffic (exhaust and nonexhaust emissions) was always present with a diminishing trend, while this trend appears to be reversed in Athens over the last 3 years. It is found that although concentrations are falling, the black carbon content of the fine aerosol fraction is not following the same trend. Changes in the regulation of the type of vehicles allowed in the urban areas may have a direct effect on the citizen's exposure to different aerosol mixture of pollutants.

Biomass burning caused by anthropogenic activity such as agriculture-burning periods (common practice during harvesting, post-harvesting, or preplanting) or naturally occurring forest fires, and domestic biofuel combustion is a frequent phenomenon causing global concern. Agricultural burning, although restricted in some countries, significantly contributes to regional air-quality deterioration and national emissions. This work focuses on atmospheric measurements at the suburbs of Athens, on August 2010, during extensive forest fires in the European Russian central plains. The effect of these fires on the measured concentrations of specific radioactive isotopes and biomass-burning tracers was studied, for long-range transport of aerosols from Russian plains. Mean total beta radioactivity was found more than 2.5 times higher during the incident compared to background values. High values were also reported for the isotope 40K, and its fluctuations were following the course of the event. 7Be showed no significant difference between the two periods, which is expected due to its origin. During the event 234Th (238U), activity concentrations were also detected. Their fluctuations showed no significant correlation with the course of the event. The average values during the period before and right after the incident is for organic carbon 2.74 μg/m3, elemental carbon 1.53 μg/m3, and for carbonate carbon 0.16 μg/m3. During the incident, the highest values were observed on August 18, with concentrations for organic carbon 5.49 μg/m3, elemental carbon 0.64 μg/m3, and carbonate carbon 0.32 μg/m3. This fact may be considered as an indicator of biomass-burning incident during the period 12–19 August 2010.

Assessment of Arctic pollution is hampered by a lack of aerosol studies in Northern Siberia. Black carbon observations were carried out at the Hydrometeorological Observatory Tiksi, a coast of Laptev sea, from September 2014 to September 2016. Aerosol sampling was accompanied by physico-chemical characterization. BC climatology showed a seasonal variation with highest concentrations from January to March (up to 450ng/m3) and lowest ones for June and September (about 20ng/m3). Stagnant weather and stable atmosphere stratification resulted in accumulation of pollution, in dependence on the wind direction and air mass transportation. Carbon fractions, functionalities, ions, and elements are associated to marine, biogenic, and continental sources. In September low OC, aliphatic, carbonyls, amines, and hydroxyls characterize background aerosols. Na+/Cl- ratio much higher than in sea-salt indicates a strong Cl depletion. Increased OC, aromatic, carbonyls, and nitrocompounds as well as waste burning markers K+, Cl-, and PO42- confirm impacts from Tiksi landfill burns. BC pollution episodes are differentiated through increased EBC and sulfates, related to gas flaring, industrial and residential emissions transported from Western Siberia while the increase of carbonyls, hydroxyl, and aromatic indicate emissions sources from Yakutia and Tiksi urban area. Arctic Haze aerosols are characterized by increased concentrations of SO42- in comparison with OC, much higher abundance of oxygenated compounds with respect to alkanes of anthropogenic origin. In summer rich organic chemistry indicates impacts of biogenic, local urban, and shipping sources as well as secondary aerosol formation influenced by emissions from low latitude Siberia.

The main objective of this study was chemical characterization and source apportionment of the oxidative potential of ambient PM2.5 samples collected in an urban background area in Athens, Greece. Ambient PM2.5 samples were collected during the summer (June-September) of 2017 and winter (February-March) of 2018 at a residential, urban background site in the outlying neighborhood of the Demokritos National Laboratory in Athens, Greece. The collected PM samples were analyzed for their chemical constituents including metals and trace elements, water-soluble organic carbon (WSOC), elemental and organic carbon (EC/OC), and marker of biomass burning (i.e., levoglucosan). In addition, the DCFH in vitro assay was performed to determine the oxidative potential of the PM2.5 samples. We performed a series of statistical analyses, including Spearman rank-order correlation analysis, principal component analysis (PCA), and multi linear regression (MLR) to determine the most significant species (as source tracers) contributing to the oxidative potential of PM2.5. Our findings revealed that the intrinsic (per PM mass) and extrinsic (per m3 of air volume) oxidative potentials of the collected ambient PM2.5 samples were significantly higher than those measured in many urban areas around the world. The results of the MLR analyses indicated that the major pollution sources contributing to the oxidative potential of ambient PM2.5 were vehicular emissions (characterized by EC) (44%), followed by secondary organic aerosol (SOA) formation (characterized by WSOC) (16%), and biomass burning (characterized by levoglucosan) (9%). The oxidative potential of the collected ambient PM2.5 samples was also higher in summer compared to the winter, mainly due to higher concentrations of EC and WSOC during this season. Results from this study corroborate the impact of traffic and SOA on the oxidative potential of ambient PM2.5 in greater Athens area, and can be helpful in adopting appropriate public health policies regarding detrimental outcomes of exposure to PM2.5.

The present study aims to investigate the sources of particulate pollution in indoor and outdoor environments, with focus on determining their contribution to the exposure of children to airborne particulate matter (PM). To this end, parallel indoor and outdoor measurements were carried out for a selection of 40 homes and 5 schools between September 2017 and October 2018. PM2.5 and PM2.5-10 samples were collected during five days in each microenvironment (ME) and analysed by X-Ray Fluorescence (XRF), for the determination of elements, and by a thermal-optical technique, for the measurement of organic and elemental carbon. The source apportionment analysis of the PM composition data, by means of the receptor model SoFi (Source Finder) 8 Pro, resulted in the identification of nine sources: exhaust and non-exhaust emissions from traffic, secondary particles, heavy oil combustion, industry, sea salt, soil, city dust, and an indoor source characterized by high levels of organic carbon. Integrated daily exposure to PM2.5 was on average 21 μg/m

The Pan-Eurasian Experiment (PEEX) Science Plan, released in 2015, addressed a need for a holistic system understanding and outlined the most urgent research needs for sustainable development in the Artic-boreal region. Air quality in China and long-range transport of the atmospheric pollutants was also indicated as one of the most crucial topics of the research agenda. This paper summarizes results obtained during the last five years in the Northern Eurasian region. It also introduces recent observations on the air quality in the urban environments in China. The main regions of interest are the Russian Arctic, Northern Eurasian boreal forests (Siberia) and peatlands and on the mega cities in China. We frame our analysis against research themes introduced in 2015. We summarize recent progress in the understanding of the land – atmosphere – ocean systems feedbacks. Although the scientific knowledge in these regions has increased, there are still gaps in our understanding of large-scale climate-Earth surface interactions and feedbacks. This arises from limitations in research infrastructures and integrative data analyses, hindering a comprehensive system analysis. The fast-changing environment and ecosystem changes driven by climate change, socio-economic activities like the China Silk Road Initiative, and the global trends like urbanization further complicate such analyses. We recognize new topics with an increasing importance in the near future, such as enhancing biological sequestration capacity of greenhouse gases into forests and soils to mitigate the climate change and the socio-economic development to tackle air quality issues.

International audience; The coming years are expected to bring rapid changes in the nanotechnology regulatory landscape, with the establishment of a new framework for nano-risk governance, in silico approaches for characterisation and risk assessment of nanomaterials, and novel procedures for the early identification and management of nanomaterial risks. In this context, Safe(r)-by-Design (SbD) emerges as a powerful preventive approach to support the development of safe and sustainable (SSbD) nanotechnology-based products and processes throughout the life cycle. This paper summarises the work undertaken to develop a blueprint for the deployment and operation of a permanent European Centre of collaborating laboratories and research organisations supporting safe innovation in nanotechnologies. The proposed entity, referred to as “the Centre”, will establish a ‘one-stop shop’ for nanosafety-related services and a central contact point for addressing stakeholder questions about nanosafety. Its operation will rely on significant business, legal and market knowledge, as well as other tools developed and acquired through the EU-funded EC4SafeNano project and subsequent ongoing activities. The proposed blueprint adopts a demand-driven service update scheme to allow the necessary vigilance and flexibility to identify opportunities and adjust its activities and services in the rapidly evolving regulatory and nano risk governance landscape. The proposed Centre will play a major role as a conduit to transfer scientific knowledge between the research and commercial laboratories or consultants able to provide high quality nanosafety services, and the end-users of such services (e.g., industry, SMEs, consultancy firms, and regulatory authorities). The Centre will harmonise service provision, and bring novel risk assessment and management approaches, e.g. in silico methodologies, closer to practice, notably through SbD/SSbD, and decisively support safe and sustainable innovation of industrial production in the nanotechnology industry according to the European Chemicals Strategy for Sustainability.

Seasonal to interannual variations in the concentrations of sulfur aerosols (

Atmospheric particles are a major environmental health risk. Assessments of air pollution related health burden are often based on outdoor concentrations estimated at residential locations, ignoring spatial mobility, time-activity patterns, and indoor exposures. The aim of this work is to quantify impacts of these factors on outdoor-originated fine particle exposures of school children. We apply nested WRF-CAMx modelling of PM

Industrial activities nearby residential areas lead to poor local air quality. Therefore, short-term exposure to an aggravated environment and the subsequent health effects should be the subject of further research. The purpose of this study is to estimate the health risks resulting from such exposure in population groups living in an industrialized area. The risk estimation was performed using different approaches suggested in relative literature. Monitoring of the air quality in an industrial zone of Attica was carried out including 24-h measurements of PM2.5 and analysis of their chemical composition for Polycyclic Aromatic Hydrocarbons and heavy metals (Pb, Cd, As, Ni, Hg, Cu, Zn). Samples of Volatile Organic Compounds were also collected. Health effects on different population subgroups were estimated for the targeted pollutants through different mathematical approaches provided by the literature, taking into consideration different parameters (e.g., age, gender, exposure duration). Inhalation rate and body weight were important parameters to estimate the exposure dose of people, and they can vary greatly depending on the age, gender, and daily activity of the person under consideration. The results indicated that the risk for potential carcinogenic and non-carcinogenic effects varies depending on the applied methodology. In any case, the acceptable limits for cancer risk provided by the OEHHA, EPA, and WHO were not exceeded.

The Arctic absorbing aerosols have a high potential to accelerate global warming. Accurate and sensitive measurements of their concentrations, variability and atmospheric mixing are needed. Filter-based aerosol light absorption measurement methods are the most widely applied in the Arctic. Those will be the focus of this study. Aerosol light absorption was measured during one month field campaign in June–July 2019 at the Pallas Global Atmospheric Watch (GAW) station in northern Finland. The campaign provided a real-world test for different absorption measurement techniques supporting the goals of the EMPIR BC metrology project in developing aerosol absorption standard and reference methods. Very low aerosol concentrations prevailed during the campaign which imposed a challenge for the instruments detection. In this study we compare the results from five filter-based absorption techniques: Aethalometer models AE31 and AE33, Particle Soot Absorption Photometer (PSAP), Multi Angle Absorption Photometer (MAAP) and Continuous Soot Monitoring System (COSMOS), and from one indirect method called Extinction Minus Scattering (EMS). The sensitivity of the filter-based techniques was adequate to measure aerosol light absorption coefficients down to around 0.05 Mm−1 levels. The average value measured during the campaign using MAAP was 0.09 Mm−1 (at wavelength of 637 nm). When data were averaged for > 1 h, an agreement of around 20 % was obtained between instruments. COSMOS measured systematically the lowest absorption coefficient values, which was expected due to the sample pre-treatment in COSMOS inlet. PSAP showed the best linear correlation with MAAP (R2 = 0.85), followed by AE33 and COSMOS (R2 = 0.84). The noisy data from AE31 resulted in a slightly lower, yet a significant, correlation with MAAP (R2 = 0.46). In contrast to the filter-based techniques, the sensitivity of the indirect EMS method to measure aerosol absorption was not adequate at such low concentrations levels. An absorption coefficient on the order of > 1 Mm−1 was estimated as the lowest limit, to reliably distinguish the signal from the noise. Throughout the campaign the aerosol was highly scattering with an average single-scattering albedo of 0.97. Two different air-mass origins could be identified: the north-east and from the north-west. The north-eastern air masses contained higher fraction of thickly coated light absorbing particles than the westerly air masses. Aerosol scattering, absorption and the particle coating thickness increased on the last ten days of the campaign during the north-eastern air flow. The simultaneous changes in aerosol source region, mixing state, concentration and particle optical size were reflected in the instruments' response in a complex way. The observed decrease in aerosol size suggested additional activation of secondary particle formation mechanisms. The results demonstrate the challenges encountered in the Arctic absorbing aerosol measurements. The applicability and uncertainties of different techniques are discussed and new knowledge on the absorbing aerosol characteristics in summer Arctic air masses reference to the source region is provided.